This invention relates to a method of ion beam depositing a diamond-like carbon (DLC) inclusive layer(s) on a substrate, including the step of heating the substrate prior to and/or during the ion beam deposition step.
Each of the aforesaid parent applications relates to a DLC inclusive coating system on a substrate. Certain embodiments of certain of the parent applications relate to hydrophobic DLC inclusive coating systems where it is desirable to deposit a coating system having a high initial contact angle xcex8.
Unfortunately, it has been found by the instant inventors that high initial contact angles xcex8 of the DLC inclusive coating systems of certain of the parent applications tend to decrease at an undesirably high rate when the coated article is exposed to ultraviolet (UV) radiation while windshield wipers are continually passed over the coating for days/weeks at a time when the coated article is being sprayed with water. This could result in a windshield that has a high contact angle xcex8 (i.e., hydrophobic nature) when originally installed on a vehicle, losing its hydrophobic characteristics over time due to a potential simultaneous combination of impinging UV radiation and windshield wiper movement over the surface of the windshield (e.g., when exposed to sun and rain in the environment which is inevitable in applications such are vehicle windshield and window applications).
It is believed by the instant inventors that weak carbon species on the surface of DLC coating system(s) may be attacked by UV radiation resulting in oxidation of the same. Such oxidation at the surface of a DLC layer may drive down contact angle xcex8 thereby rendering the coated article less hydrophobic in nature over time, especially when combined with water and windshield wiper movement across the surface of the article. Oxygen resulting from this oxidation may even react with water (e.g., rain water) to form hydrophillic surface characteristics.
Thus, it will be appreciated by those skilled in the art that there exists a need in the art for a method of depositing a diamond-like carbon (DLC) inclusive layer system (including one or more DLC inclusive layers) that results in a coated article less susceptible to losing its hydrophobic characteristics when exposed to UV radiation and windshield wiper movement across a surface thereof. There also exists a need in the art for a resulting coated article resistant to losing substantial amounts of original hydrophobic characteristics. There also exists a need in the art for a method of improving adherence of a coating system to an underlying substrate.
It is a purpose of different embodiments of this invention to fulfill any and/or all of the above described needs in the art, and/or other needs which will become apparent to the skilled artisan once given the following disclosure.
Coated articles made according to certain embodiments of this invention may be hydrophobic (e.g., shed water) in nature. In hydrophobic embodiments, an object of this invention is to provide a durable coated article that can shed or repel water (e.g. automotive windshield, automotive backlite, automotive side window, architectural window, bathroom shower glass, residential window, bathroom shower door, coated ceramic article/tile, etc.).
The hydrophobic nature of such articles is often characterized by relatively high initial contact angles xcex8. For example, coated articles herein may be characterized by an initial contact angle xcex8 (i.e. prior to being exposed to environmental tests, rubbing tests, acid tests, UV tests, or the like) of at least about 55 degrees, more preferably of at least about 80 degrees, even more preferably of at least about 100 degrees and most preferably of at least about 110 degrees.
In certain embodiments of this invention, a glass substrate upon which at least one diamond-like carbon (DLC) inclusive layer is to be ion beam deposited is heated just prior to and/or during the ion beam deposition of the DLC inclusive layer(s). Preferably, the substrate (e.g., the entire substrate, or a surface thereof upon which the DLC inclusive layer(s) is to be deposited) is heated to a temperature of from about 100-400 degrees C., more preferably from about 200-350 degrees C. During and/or shortly after such heating of the substrate, at least one DLC inclusive layer is ion beam deposited on the substrate when at least a portion of the substrate is at a relatively high temperature resulting from the heating. It is believed that this results in improved bonding of the DLC inclusive layer(s) to the underlying glass substrate and/or more tightly bonded carbon species proximate a surface of the resulting DLC inclusive layer(s). Accordingly, the resulting coated article may turn out to be more resistant to losing initial hydrophobic characteristics upon exposure to ultraviolet (UV) radiation, water and friction such as that caused by windshield wiper movement across a surface thereof.
The instant invention may be used in conjunction with various types of DLC inclusive layer systems and is not intended to be limiting in that regard.
This invention will now be described with respect to certain embodiments thereof, along with reference to the accompanying illustrations.